1. Field of the Invention
The present invention relates primarily to a tandem type master cylinder used for a dual hydraulic brake system in automobiles, and more particularly, to a tandem type master cylinder having a cylinder body provided with a single oil tank.
2. Description of the Prior Art
In a master cylinder of the type as described and heretofore known, a cylinder body has a cylinder bore in which are defined a pair of independent first and second hydraulic power chambers by means of a pair of front and rear pistons slidably received in the cylinder bore. The cylinder body is formed at its upper side with an auxiliary oil reservoir having first and second reservoir chambers defined by a partition and placed in communication with the first and second hydraulic power chambers, respectively, the auxiliary oil reservoir being formed at its upper end with a main oil reservoir in communication with both the reservoir chambers. This conventional master cylinder is advantageous in that a single supply of oil into the oil reservoir will suffice and hence replenishment of oil is simple; only one set of oil detectors need be provided on the main oil reservoir; and even if oil leakage should occur in either one of the two hydraulic circuits in communication with the first and second hydraulic power chambers, the other normal circuit is prevented from being evacuated. On the other hand, the aforementioned prior art master cylinder suffers from the disadvantages in that since the auxiliary oil reservoir is provided at one point of the cylinder body, a communicating oil passage connecting the auxiliary oil reservoir and one of the hydraulic power chambers remote therefrom inevitably becomes lengthened, and therefore, bubbles generated in the oil tend to stay in the oil passage.